Roller cutter



y RQRCRUM 2,216,938

RDLLER CUTTER Y Filed sept; 12, 193s INVENTQ Pobra/. 'um

. TTgRyAEY A*BY /M/ Patented Oct. 8, 1940 UNITED sTATEs PATENT oFFicE N i 2,216,938 nonna corran nonna n. Crum, Whittier, oeuf. Appueauen september 12, 193s, serial No. 229,574

8 Claims.

rotary drill string. One or `more inner cutters are used, arranged for tree rotation about axes r radial to the drill string axis, for cutting along the center portion of the `bore bottom. These cutters may be supplemented by outside cutters, usually of disc form, adapted to operate on an outer zone. `mud fluid circulation is maintained by way of 9U an aperture extending through the drill string and past the cutters. tended,` among other things, to keep 1the rows of teeth of the cutters free fromthe disintegrated matter removed by the bit.

35 It is one of the objects of this invention to make it possible to circulate the mud fluid more easily past the teeth of the inner cutters.

It has been common to provide teeth for inner cutters arranged in a series of separate, annular 30 rows. The spaces between the annular rows are necessarily quite restricted, for it is obviously desirable to have as much `of the toothed area in contact with the hole bottom as possible. However, such spaces are readily clogged or balled 35 up with the bore cuttings. It is another object of this invention so to arrange the teeth that they are effective in operating on the bore bottom, and yet do notreadily accumulate any foreign matter, but instead, the circulating mud 10 fluid can maintain the teeth clean.

This object is attained by'iorming the teeth in general helical like rows; and'prei'erably in the form of multiple threads. Thus the successive teeth have a progressive radial action on the bore i5 bottom; and the space between adjacent teeth may be quite large.

In forming one or more helical-like rows of teeth, ltis readily seen that those teeth which approach the end` surface of the cutter are suc- During the process of drilling, a,

This' circulation is inbuilding upl their cutting 4edges so that these edges extend entirely to the plae defining the end oi.' the cutter. In this way, the cutters are eifective over the bottom of the bore, from the axis of the rotary drill to the outer end surface I of the cutter.

Thisv ,invention possesses many other advanl tages, and has other objects which may be made more easily apparent from a consideration of one embodiment of the invention. For this purpose l there is shown a form in the drawing accom-- panying and forming part of the present `speci-- iication. This i'orm will now be described in detail, illustrating. the general principles of the invention; but it is to be understood that this u `detailed description is not to be taken in a limiting sense, since thescope of this invention is best defined by the appended claims.

Referring to the drawing: Figure 1 is an elevation of a roller cutter em- 20 j bodying the invention; 1

Fig. 2 is an end view taken from the left hand end of Fig. 1; and v,

Fig. 3 is a fragmentary enlarged view of the end' portion of the cutter, shown in developed 25 form.

The roller cutter is shown as having a` body l. This body I tapers from a large end 2 to a small end 3. It is provided with a through aperture to permit it, as well as Ianother inner cutter of theA same construction, to be supported in the manner illustrated inV the application hereinbefore identified; that is, on a pin extending diametrically with respect to the axis of the drill bit, and across the bottom of the bit. The smaller end 3 of each of the two cutters is dis-. posed adjacent the axis of the bit.

Teeth 4, 5, etc. are arranged on the 'outer surface of the body I.` `These teeth are formed by i sloping sides converging to'ia sharp top edge or 40 point 6.

In order that there may be adequate spacing between the teeth 4, 5, etc. these teeth are arranged in helical-like rows, about the axis of rotation of the cutter body." In the present instance, two separate helical-like rows, forming a multiple thread-like conformation are illustrated, although single threads or any other multiple thread arrangement may be used. `At any rate, 5o

one helical-like row, for example, may begin with t the tooth 1 at the large end of the body l and ends with the tooth 8 at the small end l of the body' l. As illustrated most clearly inFig. 2, another helical-like row begins at thetooth l 'diametricaily opposite the tooth'fljand finally?l ends with the tooth-I0 at the small end. Y

time `the teeth in. each helical-like row actin I and preventing material hailing up. At the same AAsuccession uponthe bottom of the bore, to disintegrate the material. A

As shown mostcieajriy in Fig. 1, the teetnsuh ,4 as 1',v II, and I2, adjacent the end 2 of the cutter,

A` entirelength, and to ter, the p'oir'its I3,'I.I and viated by the plane normal f cutter structure and: defining the large end l 1 to ensure that the cutter :will be active along the are'not' complete teeth, their sides being abbreto the .axis ofthe ,thereof. In order to' strengthen these teeth and' 2. simi1ar1y,trie cutting edge leef tooth i2 has asimilar'extension I8. These extensions may be `formed conveniently by building up these teeth by hard facing material, such asY Stellite or a tungsten carbide compound,

Theteeth i, I9 and 20 diametrically opposite `from teeth 1.

II and I2 may ,be similarly built up as indicated by the shaded areas 2 I 22 and 23.

1I; These .extensions formed of the hard facing ymaterial serve toreinforce ,the narrow teeth .where the helical rows begin',

and also yensure that the cutter structurev will be effective for its entire length. up to the surface defining the large A end 2. Y.

What is claimed is: .1. In `a rotary cutter for .drill bits, a cutter body, and a rowof cutter teeth thereon in helical- 4like formation with respect to the axis of the 'bOdY.

cuttingedges, the teeth adjacent the end of the row each having one said teeth having sides converging to form side at least partly defined by a continuation of the end surface of the cutter body, said end teeth each having an extension of the cutting edge in a direction transverse to said cutter end surface and to the said cutting edge. 2. In a rotary cutter, for drill bits, a cutter body, a row of cutter teeth thereon in helicallike formation with respect to the axis of the body, said teeth having sides converging to form tooth points, the teeth adjacent the end of the row each having one side at least partlydefined by a continuationI of the end surface of the cutter body, and hard facing material forming an extension of each of said end teeth in a direction transverse to said cutter end surface and to the direction of the row.

3. In a roller cutter for drill bits, a cutter body,

- rthey teeth may kept rather widelyv spaced, #giving a. free courseI for the ,circulationof mud fluid between the teethaA row of cutter teeth thereon in heli'csal-like' Yformation with respectto'theaxis of `the body.

said teeth having sides converging to form cutting edges. each of the teeth adiacent the end of the l I row one side at least partly deiined'bya jcontinuation of the end surface of the cutterbody, and al reenforcement foreach of saidY end 1teeth,'comprising a body of hard facing material on the tooth, having converging sides forming a cutting edge extending from the helical cuttini edge of the tooth to said continuation of the end surface of the cutter body and transverse to said surface aswell as to said helical cutting edge.

4. In a roller cutter for drill bits, a cutter body, a row. of cutter teeth thereon in helical-like formation with respect to the axis of the body, said teeth having sides converging to form cutting edges, each of the teeth adjacent the end of the row having one side at least partly defined by a continuation of the end surface of the cutter body, and reenforcing means for each of said end teeth, said means also forming a cutting edge extending from the helical cutting edge of the tooth to said continuation of the end surface of the body.

5. In a roller cutter for drill bits, a cutter body, and a row of cutter teeth thereon arranged in helical-like formation with respect to the axis ofthe body, said teeth having cutting edges of substantial length in the direction ofthe helicallike row, there being uninterrupted channels extending from end to end 'of the body and intersecting the said row, adjacent sidesof neighbor;` l ing channels serving to define the'sidesof said taperedy t cutter body, and a row of cutter teethithereon edges of substantial length in the direction of the helical-likeY row, there being uninterrupted chanl arranged in screW-thread-like formation, saidv teeth having cutting edges of substantial length in the direction `of the row, the pitch-angle of the thread of said formation being such that said thread maires-` substantially more than a complete turn in the length of the body.

8. In a roller cutter for drill bits, a tapered cutter body, and a plurality of rows of cutter teeth thereon, said rows being arranged in multiple screw-thread-like formation, said teeth having cutting edges of substantial llength in the direc.- tion of the row, the pitch angle 'off the threads of said formation being relatively small, so that at least one of said threads makes substantially more than a complete turn in the length ofthe body, there being uninterrupted channels extending from end toend ofthe body along elements of the surface of the body.

1 arranged in helical-like formationwith respectVV to the axis of the body, said teeth having cuttingf` 'Y .ROLAND R. CRUM. 

